add tracing

src/args.rs

@@ -57,18 +57,20 @@ pub struct AppendCmd {
 }
 
 #[derive(Debug, Clone, PartialEq, clap::Subcommand)]
+#[command(flatten_help = true)]
 pub enum Subcommand {
     Append(AppendCmd),
 }
 
 #[derive(Debug, Clone, PartialEq, clap::Parser)]
-#[command(version, about, author, arg_required_else_help(true))]
+#[command(version, about, author)]
+#[command(arg_required_else_help(true), args_override_self(true))]
 #[command(propagate_version = true)]
 pub struct Args {
-    #[arg(long, default_value = "auto")]
+    #[arg(long, global(true), default_value = "auto")]
     pub color: ColorChoice,
 
-    #[arg(long)]
+    #[arg(long, global(true), default_value = "./configuration.nix")]
     pub file: Arc<OsStr>,
 
     #[command(subcommand)]

src/color.rs

@@ -6,10 +6,14 @@ use std::{
 #[allow(unused_imports)]
 use crate::prelude::*;
 
-pub static CLI_ENABLE_COLOR: OnceLock<bool> = OnceLock::new();
+/// The actual, final value for whether color should be used, based on CLI and environment values.
+pub static SHOULD_COLOR: LazyLock<bool> = LazyLock::new(|| is_clicolor_forced() || is_color_reqd());
+
+/// Initialized from the `--color` value from the CLI, along with `io::stdin().is_terminal()`.
+pub static _CLI_ENABLE_COLOR: OnceLock<bool> = OnceLock::new();
 
 fn is_color_reqd() -> bool {
-    CLI_ENABLE_COLOR.get().copied().unwrap_or(false)
+    _CLI_ENABLE_COLOR.get().copied().unwrap_or(false)
 }
 
 fn is_clicolor_forced() -> bool {
@@ -24,8 +28,6 @@ fn is_clicolor_forced() -> bool {
         .unwrap_or(false)
 }
 
-pub static SHOULD_COLOR: LazyLock<bool> = LazyLock::new(|| is_clicolor_forced() || is_color_reqd());
-
 /// Silly wrapper around LazyLock<&'static str> to impl Display.
 pub(crate) struct _LazyLockDisplay(LazyLock<&'static str>);
 impl Display for _LazyLockDisplay {
@@ -47,8 +49,5 @@ pub(crate) const ANSI_CYAN: _LazyLockDisplay = _LazyLockDisplay(LazyLock::new(||
 }));
 
 pub(crate) const ANSI_RESET: _LazyLockDisplay = _LazyLockDisplay(LazyLock::new(|| {
-    SHOULD_COLOR
-        // C'mon rustfmt, just format it to match ^.
-        .then_some("\x1b[0m")
-        .unwrap_or_default()
+    SHOULD_COLOR.then_some("\x1b[0m").unwrap_or_default()
 }));

src/lib.rs

@@ -27,6 +27,8 @@ pub(crate) mod prelude {
     pub use fs_err::os::unix::fs::{FileExt, OpenOptionsExt};
 
     pub use tap::{Pipe, Tap};
+
+    pub use tracing::{Level, debug, error, info, trace, warn};
 }
 
 use prelude::*;
@@ -34,7 +36,7 @@ use prelude::*;
 pub mod args;
 pub use args::{AppendCmd, Args};
 mod color;
-pub use color::{CLI_ENABLE_COLOR, SHOULD_COLOR};
+pub use color::{_CLI_ENABLE_COLOR, SHOULD_COLOR};
 pub mod line;
 mod nixcmd;
 pub use line::Line;
@@ -47,6 +49,7 @@ use crate::source::SourceFile;
 
 pub const ASCII_WHITESPACE: &[char] = &['\t', '\n', '\x0C', '\r', ' '];
 
+#[tracing::instrument(level = "debug")]
 pub fn do_append(args: Arc<Args>, append_args: AppendCmd) -> Result<(), BoxDynError> {
     let filepath = Path::new(&args.file);
     let filepath: PathBuf = if filepath.is_relative() && !filepath.starts_with("./") {

src/main.rs

@@ -3,13 +3,14 @@ use std::process::ExitCode;
 use std::{error::Error as StdError, sync::Arc};
 
 use clap::{ColorChoice, Parser as _};
+use tracing_human_layer::HumanLayer;
+use tracing_subscriber::util::SubscriberInitExt;
+use tracing_subscriber::{EnvFilter, layer::SubscriberExt};
 
 fn main_wrapped() -> Result<(), Box<dyn StdError + Send + Sync + 'static>> {
     let args = Arc::new(dynix::Args::parse());
 
-    dbg!(&args);
-
-    let success = dynix::CLI_ENABLE_COLOR.set(match args.color {
+    let success = dynix::_CLI_ENABLE_COLOR.set(match args.color {
         ColorChoice::Always => true,
         ColorChoice::Auto => io::stdin().is_terminal(),
         ColorChoice::Never => false,
@@ -18,6 +19,13 @@ fn main_wrapped() -> Result<(), Box<dyn StdError + Send + Sync + 'static>> {
         success.expect("logic error in CLI_ENABLE_COLOR");
     }
 
+    tracing_subscriber::registry()
+        .with(HumanLayer::new().with_color_output(*dynix::SHOULD_COLOR))
+        .with(EnvFilter::from_default_env())
+        .init();
+
+    tracing::debug!("Parsed command-line arguments: {args:?}");
+
     use dynix::args::Subcommand::*;
     match &args.subcommand {
         Append(append_args) => dynix::do_append(args.clone(), append_args.clone())?,

src/source.rs

@@ -102,6 +102,11 @@ pub struct SourceFile {
 impl SourceFile {
     /// Panics if `path` is a directory path instead of a file path.
     pub fn open_from(path: Arc<Path>, options: OpenOptions) -> Result<Self, IoError> {
+        trace!(
+            "SourceFile::open_from(path={:?}, options={:?})",
+            path,
+            options.options(),
+        );
         assert!(path.file_name().is_some());
 
         let file = Arc::new(Mutex::new(options.open(&*path)?));